arXiv papers from December 2006

P. W. Ng, Wilhelm Winter

Let X be a path connected, compact metric space and let A be a unital separable simple nuclear Z-stable real rank zero C*-algebra. We classify all the unital *-embeddings (up to approximate unitary equivalence) of C(X) into A. Specifically, we provide an existence and a uniqueness theorem for unital *-embeddings from C(X) into A.

Homer G. Ellis

Giving up Einstein's assumption, implicit in his 1916 field equations, that inertial mass, even in its appearance as energy, is equivalent to active gravitational mass and therefore is a source of gravity allows revising the field equations to a form in which a positive cosmological constant is seen to (mis)represent a uniform negative net mass density of gr

M. A. Stephanov

The aim of this review is to summarize the contemporary understanding of the QCD phase diagram as a function of temperature and baryo-chemical potential. The focus is on recent theoretical developments due to lattice simulations of the phase diagram.

X. Lou, C. Adelmann, S. A. Crooker, E. S. Garlid

A longstanding goal of research in semiconductor spintronics is the ability to inject, modulate, and detect electron spin in a single device. A simple prototype consists of a lateral semiconductor channel with two ferromagnetic contacts, one of which serves as a source of spin-polarized electrons and the other as a detector. Based on work in analogous metall

M. D. Iftime

One of the biggest challenges to theoretical physics of our time is to find a background-independent quantum theory of gravity. Today one encounters a profusion of different attempts at quantization, but no fully accepted - or acceptable, theory of quantum gravity. Any such approach requires a response to a question that lies at the heart of this problem. ``

Donald R. King

Let G be a connected linear semisimple Lie group with Lie algebra g and maximal compact subgroup K. Let K_C -> Aut(p_C) be the complexified isotropy representation at the identity coset of the corresponding symmetric space. Suppose that O is a nilpotent K_C-orbit in p_C, and bar(O} is its Zariski closure in p_C. We study the K-type decomposition of the ring

Claire M. Postlethwaite, Mary Silber

Previous work has shown that Benjamin-Feir unstable traveling waves of the complex Ginzburg-Landau equation (CGLE) in two spatial dimensions cannot be stabilized using a particular time-delayed feedback control mechanism known as `time-delay autosynchronisation'. In this paper, we show that the addition of similar spatial feedback terms can be used to stabil

Y. Hashimoto, Y. Murakami, S. Maruyama, J. Kono

We have performed polarization-dependent ultrafast pump-probe spectroscopy of a film of aligned single-walled carbon nanotube bundles. By taking into account imperfect nanotube alignment as well as anisotropic absorption cross sections, we quantitatively determined distinctly different photo-bleaching dynamics for polarizations parallel and perpendicular to

Axel Krause

An attractive mechanism to break supersymmetry in vacua with zero vacuum energy arose in E_8 x E_8 heterotic models with hidden sector gaugino condensate. An H-flux balances the exponentially small condensate on shell and fixes the complex structure moduli. At quantum level this balancing is, however, obstructed by the quantization of the H-flux. We show tha

J. W. Fowler, M. D. Niemack, S. R. Dicker, A. M. Aboobaker

The Atacama Cosmology Telescope is a 6-meter telescope designed to map the Cosmic Microwave Background simultaneously at 145 GHz, 215 GHz, and 280 GHz with arcminute resolution. Each frequency will have a 32 by 32 element focal plane array of TES bolometers. This paper describes the design of the telescope and the cold reimaging optics, which is optimized fo

Dylan Menzies, Grant J. Mathews

It has recently been suggested that observed galaxy rotation curves can be accounted for by general relativity without recourse to dark-matter halos. A number of objections have been raised, which have been addressed by the authors. Here, the calculation of tangential velocity is questioned.

A. J. Barth

Since its discovery, Malin 1 has been considered the prototype and most extreme example of the class of giant low surface brightness disk galaxies. Examination of an archival Hubble Space Telescope I-band image reveals that Malin 1 contains a normal stellar disk that was not previously recognized, having a central I-band surface brightness of mu_0 = 20.1 mag

Armen Sedrakian

This article provides a concise review of the problem of neutrino radiation from dense matter. The subjects addressed include quantum kinetic equations for neutrino transport, collision integrals describing neutrino radiation through charged and neutral current interactions, radiation rates from pair-correlated baryonic and color superconducting quark matter

Paul F. Baum, Piotr M. Hajac, Rainer Matthes, Wojciech Szymanski

We recast basic topological concepts underlying differential geometry using the language and tools of noncommutative geometry. This way we characterize principal (free and proper) actions by a density condition in (multiplier) C*-algebras. We introduce the concept of piecewise triviality to adapt the standard notion of local triviality to fibre products of C

S. Ryu, O. I. Motrunich, J. Alicea, Matthew P. A. Fisher

There is growing evidence from both experiment and numerical studies that low half-odd integer quantum spins on a kagome lattice with predominant antiferromagnetic near neighbor interactions do not order magnetically or break lattice symmetries even at temperatures much lower than the exchange interaction strength. Moreover, there appear to be a plethora of

Edward J. Su, Saijun Wu, Mara Prentiss

We demonstrate a standing wave light pulse sequence that places atoms into a superposition of displaced wavepackets with precisely controlled displacements that remain constant for times as long as 1 s. The separated wavepackets are subsequently recombined resulting in atom interference patterns that probe energy differences of approximately 10^-34 J, and ca

Homer G. Ellis

In creating his gravitational field equations Einstein unjustifiedly assumed that inertial mass, and its energy equivalent, is a source of gravity. Denying this assumption allows modifying the field equations to a form in which a positive cosmological constant appears as a uniform density of gravitationally repulsive matter. This repulsive matter is identifi

Francesca Borzumati, Torsten Bringmann, Piero Ullio

The generation of dark matter in late decays of quasi-stable massive particles has been proposed as a viable framework to address the excess of power found in numerical N-body simulations for cold dark matter cosmologies. We identify a convenient set of variables to illustrate which requirements need to be satisfied in any generic particle physics model to a

Sergey Kitaev, Toufik Mansour, Jeffrey B. Remmel

Recently, Kitaev and Remmel [Classifying descents according to parity, Annals of Combinatorics, to appear 2007] refined the well-known permutation statistic ``descent'' by fixing parity of one of the descent's numbers. Results in that paper were extended and generalized in several ways. In this paper, we shall fix a set partition of the natural numbers $N$,

Kurusch Ebrahimi-Fard, Jose M. Gracia-Bondia, Frederic Patras

The word problem for an arbitrary associative Rota-Baxter algebra is solved. This leads to a noncommutative generalization of the classical Spitzer identities. Links to other combinatorial aspects, particularly of interest in physics, are indicated.

Martin Goldstern, Michael Pinsker

A clone on a set X is a set of finitary operations on X which contains all projections and which is moreover closed under functional composition. Ordering all clones on X by inclusion, one obtains a complete algebraic lattice, called the clone lattice. We summarize what we know about the clone lattice on an infinite base set X and formulate what we consider

Son-Hsien Chen, Ming-Hao Liu, Ching-Ray Chang

The intrinsic spin-Hall effect in hexagon-shaped samples is investigated. To take into account the spin-orbit couplings and to fit the hexagon edges, we derive the triangular version of the tight-binding model for the linear Rashba [Sov. Phys. Solid State 2, 1109 (1960)] and Dresselhaus [Phys. Rev. 100, 580 (1955)] [001] Hamiltonians, which allow direct appl

I. Snyman, Y. V. Nazarov

We study a voltage-driven quantum point contact (QPC) strongly coupled to a qubit. We predict pronounced observable features in the QPC current that can be interpreted in terms of half-integer charge transfers. Our analysis is based on the Keldysh generating functional approach and contains general results, valid for all coherent conductors.

Pavel Ginzburg, Meir Orenstein

We propose a novel concept of left-handed metamaterial assembly by semiconductor based low-dimensional quantum structures. We theoretically demonstrate the left-handed material, combined from low-dimensional semiconductor quantum wells or quantum dots. One of the most important advantages of the proposed scheme is the possible controllability of material reg

David Atwood, Shaouly Bar-Shalom, Amarjit Soni

A charged Higgs pair can be produced at an ee collider through a t-channel exchange of a heavy neutrino (N) via e^+ e^- -> H^+ H^- and, if N is a Majorana particle, also via the lepton number violating (LNV) like-sign reaction e^\pm e^\pm \to H^\pm H^\pm. Assuming no a-priori relation between the effective eNH^+ coupling (\xi) and light neutrino masses, we s

Ozlem Beyarslan

We construct a random $n$-hypergraph for every $n$, in a given pseudofinite field.

Jure Zupan

A review of methods to extract the standard CKM unitarity triangle angle alpha is provided. The sizes of related theoretical errors are reviewed.

Orlando Ragnisco, Federico Zullo

Most of the work done in the past on the integrability structure of the Classical Heisenberg Spin Chain (CHSC) has been devoted to studying the $su(2)$ case, both at the continuous and at the discrete level. In this paper we address the problem of constructing integrable generalized ''Spin Chains'' models, where the relevant field variable is represented by

R. J. Sault, G. J. Carrad, P. J. Hall, J. Crofts

Path length changes through the atmosphere cause significant errors for astronomical radio interferometry at high frequencies (e.g. 100 GHz). Path length differences typically give rise to a differential excess path of 1mm for antennas separated by 1km, and have fluctuation time scales of greater than 10 seconds. To measure these fluctuations, we are buildin

Gao-Feng Gu, Wei Chen, Wei-Xing Zhou

The statistical properties of the bid-ask spread of a frequently traded Chinese stock listed on the Shenzhen Stock Exchange are investigated using the limit-order book data. Three different definitions of spread are considered based on the time right before transactions, the time whenever the highest buying price or the lowest selling price changes, and a fi

C. Arezzo, F. Pacard, M. Singer

Given a compact Kahler manifold with an extremal metric (M,\omega), we give sufficient conditions on finite sets points p_1,...,p_n and weights a_1,...a_n for which the blow up of M at p_1,...,p_n has an extremal metric in the Kahler class \pi^*[\omega] - \epsilon (a_1 PD[E_1] + .. + a_n PD[E_n]) for all \epsilon sufficiently small. In particular our result

Yuri A. Rylov

It is shown that the Euler system of hydrodynamic equations for inviscid barotropic fluid for density and velocity is not a complete system of dynamic equations for the inviscicd barotropic fluid. It is only a closed subsystem of four dynamic equation. The complete system of dynamic equation consists of seven dynamic equations for seven dependent variables:

Stanislaw Mrowczynski, Markus H. Thoma

Since the quark-gluon plasma (QGP) reveals some obvious similarities to the well-known electromagnetic plasma (EMP), an accumulated knowledge on EMP can be used in the QGP studies. After discussing similarities and differences of the two systems, we present theoretical tools which are used to describe the plasmas. The tools include: kinetic theory, hydrodyna

S Carloni, J A Leach, S Capozziello, P K S Dunsby

We study the phase--space of FLRW models derived from Scalar--Tensor Gravity where the non--minimal coupling is $F(\phi)=\xi\phi^2$ and the effective potential is $V(\phi)=\lambda \phi^n$. Our analysis allows to unfold many feature of the cosmology of this class of theories. For example, the evolution mechanism towards states indistinguishable from GR is rec

Juan Garcia-Bellido, Daniel G. Figueroa

The process of reheating the universe after hybrid inflation is extremely violent. It proceeds through the nucleation and subsequent collision of large concentrations of energy density in bubble-like structures, which generate a significant fraction of energy in the form of gravitational waves. We study the power spectrum of the stochastic background of grav

Adrian Ioana

We prove that if a countable group $\Gamma$ contains a copy of $\Bbb F_2$, then it admits uncountably many non orbit equivalent actions.

Ken-ichi Ohshima

We show that the correct entropy, temperature (and absorption probability) of non-extremal black p-brane can be reproduced by a certain thermodynamical model when maximizing its entropy. We show that the form of the model is related to the geometrical similarity of non-extremal and near extremal black p-brane at near horizon region, and argue about the appro

Kiyonori Gomi

This is an expository account of the following result: we can construct a group by means of twisted Z_2-graded vectorial bundles which is isomorphic to K-theory twisted by any degree three integral cohomology class.

Jawad Y. Abuhlail

In this paper we introduce and investigate top (bi)comodules} of corings, that can be considered as dual to top (bi)modules of rings. The fully coprime spectra of such (bi)comodules attains a Zariski topology, defined in a way dual to that of defining the Zariski topology on the prime spectra of (commutative rings. We restrict our attention in this paper to

Chenchang Zhu

Following Sullivan's spacial realization of a differential algebra, we construct a universal integrating Lie 2-groupoid for every Lie algebroid. Then We show that unlike Lie algebras which one-to-one correspond to simply connected Lie groups, Lie algebroids (integrable or not) one-to-one correspond to a sort of etale Lie 2-groupoids with 2-connected source f

Lili Hu, Chunhui Lai

In this paper, we characterize the potentially $(K_5-C_4)$-graphic sequences where $K_5-C_4$ is the graph obtained from $K_5$ by removing four edges of a 4 cycle $C_4$. This characterization implies a theorem due to Lai [6].

Igor V. Ovchinnikov, Lizette A. Bartell, Daniel Neuhauser

In a previous work we developed a family of orbital-free tensor equations for DFT [J. Chem. Phys. 124, 024105 (2006)]. The theory is a combination of the coupled hydrodynamic moment equations hierarchy with a cumulant truncation of the one-body electron density matrix. A basic ingredient in the theory is how to truncate the series of equation of motion for t

F. Blanco, F. Fichera, P. La Rocca, F. Librizzi

Experiments concerning the physics of cosmic rays offer to high-school teachers and students a relatively easy approach to the field of research in high energy physics. The detection of cosmic rays does not necessarily require the use of sophisticated equipment, and various properties of the cosmic radiation can be observed and analysed even by the use of a

Namit Mahajan, Sukanta Panda

We explore the possibility of utilizing the prompt muon fluxes at very high energies in order to discriminate various models/parametrizations of low-x QCD behaviour of hadronic cross-sections relevant at such energies. We find that the pair meter technique for measuring high energy prompt muons can be very efficient in such an endeavor. As a by product, it a

Kanabu Nawa, Hideo Suganuma, Toru Kojo

We study baryons in holographic QCD with $D4/D8/\bar{D8}$ multi $D$ brane system. In holographic QCD, the baryon appears as a topologically non-trivial chiral soliton in a four-dimensional effective theory of mesons, which is called `Brane-induced Skyrmion'. We derive and calculate the Euler-Lagrange equation for the hedgehog configuration with chiral profil

Ilia Negri, Yoichi Nishiyama

A goodness of fit test for the drift coefficient of an ergodic diffusion process is presented. The test is based on the score marked empirical process. The weak convergence of the proposed test statistic is studied under the null hypotheses and it is proved that the limit process is a continuous Gaussian process. The structure of its covariance function allo

Yoichi Ikeda, Toru Sato

KNN three body resonance has been studied by KNN-pi Sigma N coupled channel Faddeev equation. The S-matrix pole has been investigated using the analytically continued scattering amplitude on the unphysical Riemann sheet. As a result we found a three-body resonance of strange dibaryon system with the binding energy and width B=76MeV and \Gamma=54MeV.

Y. Ben-Aryeh

The possibility of measuring the second order correlation function of the gravitational waves detectors' currents or photonumbers, and the observation of the gravitational signals by using a spectrum analyzer is discussed. The method is based on complicated data processing and is expected to be efficient for coherent periodic gravitational waves. It is sugge

Shant Baghram, Marzieh Farhang, Sohrab Rahvar

Here in this work we propose a modified gravity with the action of $f(R) = \sqrt{R^2 - R_0^2}$ instead of Einstein-Hilbert action to describe the late time acceleration of the universe. We obtain the equation of the modified gravity both in the metric and Palatini formalisms. An asymptotic solution of gravity equations corresponding to a constant Ricci scala

Juan Li, Shanjian Tang

A local strict comparison theorem and some converse comparison theorems are proved for reflected backward stochastic differential equations under suitable conditions.

Jinghua Lan, Baowen Li

We study thermal rectifying effect in two dimensional (2D) systems consisting of the Frenkel Kontorva (FK) lattice and the Fermi-Pasta-Ulam (FPU) lattice. It is found that the rectifying effect is related to the asymmetrical interface thermal resistance. The rectifying efficiency is typically about two orders of magnitude which is large enough to be observed

John O. Fjaerestad, Weihong Zheng, Rajiv R. P. Singh, Ross H. McKenzie

We use series expansion methods to study ground- and excited-state properties in the helically ordered phase of spin-1/2 frustrated antiferromagnets on an anisotropic triangular lattice. We calculate the ground state energy, ordering wavevector, sublattice magnetization and one-magnon excitation spectrum for parameters relevant to Cs_2CuCl_4 and Cs_2CuBr_4.

S. Rezakhah, S. Shemehsavar

Let $Q_n(x)=\sum_{i=0}^{n} A_{i}x^{i}$ be a random polynomial where the coefficients $A_0,A_1,... $ form a sequence of centered Gaussian random variables. Moreover, assume that the increments $\Delta_j=A_j-A_{j-1}$, $j=0,1,2,...$ are independent, assuming $A_{-1}=0$. The coefficients can be considered as $n$ consecutive observations of a Brownian motion. We

Peyman Afshani, Hamed Hatami

We prove algorithmic and hardness results for the problem of finding the largest set of a fixed diameter in the Euclidean space. In particular, we prove that if $A^*$ is the largest subset of diameter $r$ of $n$ points in the Euclidean space, then for every $\epsilon>0$ there exists a polynomial time algorithm that outputs a set $B$ of size at least $|A^*|$

Hamed Hatami, Pooya Hatami

We study the structure of a minimum dominating set of $C_{2n+1}^n$, the Cartesian product of $n$ copies of the cycle of size $2n+1$, where $2n+1$ is a prime.

Hamed Hatami, Hossein Maserrat

Suppose we have a family ${\cal F}$ of sets. For every $S \in {\cal F}$, a set $D \subseteq S$ is a {\sf defining set} for $({\cal F},S)$ if $S$ is the only element of $\cal{F}$ that contains $D$ as a subset. This concept has been studied in numerous cases, such as vertex colorings, perfect matchings, dominating sets, block designs, geodetics, orientations,

Mark R. Dowling, Michael A. Nielsen

Determining the quantum circuit complexity of a unitary operation is closely related to the problem of finding minimal length paths in a particular curved geometry [Nielsen et al, Science 311, 1133-1135 (2006)]. This paper investigates many of the basic geometric objects associated to this space, including the Levi-Civita connection, the geodesic equation, t

Keqin Liu

We introduce 3-irreducible modules, even roots and odd roots for Leibniz algebras, produce a basis for a root space of a Leibniz algebra with a semisimple Lie factor, and classify finite dimensional simple Leibniz algebras with Lie factor $s\ell_2$.

Hamed Hatami, Ruzbeh Tusserkani

Circular chromatic number, $\chi_c$ is a natural generalization of chromatic number. It is known that it is \NP-hard to determine whether or not an arbitrary graph $G$ satisfies $\chi(G) = \chi_c(G)$. In this paper we prove that this problem is \NP-hard even if the chromatic number of the graph is known. This answers a question of Xuding Zhu. Also we prove t

Peyman Afshani, Mahsa Ghandehari, Mahya Ghandehari, Hamed Hatami

This paper proves that if $G$ is a graph (parallel edges allowed) of maximum degree 3, then $\chi_c'(G) \leq 11/3$ provided that $G$ does not contain $H_1$ or $H_2$ as a subgraph, where $H_1$ and $H_2$ are obtained by subdividing one edge of $K_2^3$ (the graph with three parallel edges between two vertices) and $K_4$, respectively. As $\chi_c'(H_1) = \chi_c'

Mahya Ghandehari, Hamed Hatami, Ebadollah S. Mahmoodian

A critical set in an $n \times n$ array is a set $C$ of given entries, such that there exists a unique extension of $C$ to an $n\times n$ Latin square and no proper subset of $C$ has this property. For a Latin square $L$, $\scs{L}$ denotes the size of the smallest critical set of $L$, and $\scs{n}$ is the minimum of $\scs{L}$ over all Latin squares $L$ of or

Hamed Hatami, Ebadollah S. Mahmoodian

A critical set in an $n \times n$ array is a set $C$ of given entries, such that there exists a unique extension of $C$ to an $n\times n$ Latin square and no proper subset of $C$ has this property. The cardinality of the largest critical set in any Latin square of order $n$ is denoted by $\lcs{n}$. We give a lower bound for $\lcs{n}$ by showing that $\lcs{n}

Hamed Hatami

We prove that a random cubic graph almost surely is not homomorphic to a cycle of size 7. This implies that there exist cubic graphs of arbitrarily high girth with no homomorphisms to the cycle of size 7.

Hamed Hatami

An adjacent vertex distinguishing edge-coloring or an \avd-coloring of a simple graph $G$ is a proper edge-coloring of $G$ such that no pair of adjacent vertices meets the same set of colors. We prove that every graph with maximum degree $\Delta$ and with no isolated edges has an \avd-coloring with at most $\Delta+300$ colors, provided that $\Delta >10^{20}$

Ehud Hrushovski, Ben Martin, Silvain Rideau, Raf Cluckers

We prove that the theory of the $p$-adics ${\mathbb Q}_p$ admits elimination of imaginaries provided we add a sort for ${\rm GL}_n({\mathbb Q}_p)/{\rm GL}_n({\mathbb Z}_p)$ for each $n$. We also prove that the elimination of imaginaries is uniform in $p$. Using $p$-adic and motivic integration, we deduce the uniform rationality of certain formal zeta functio

P. Plochocka-Polack, J. G. Groshaus, M. Rappaport, V. Umansky

We study the absorption spectrum of a two-dimensional electron gas (2DEG) in a magnetic field. We find that that at low temperatures, when the 2DEG is spin polarized, the absorption spectra, which correspond to the creation of spin up or spin down electron, differ in magnitude, linewidth and filling factor dependence. We show that these differences can be ex

Stefan Laendner, Thorsten Hehn, Olgica Milenkovic, Johannes B. Huber

We generalize the notion of the stopping redundancy in order to study the smallest size of a trapping set in Tanner graphs of linear block codes. In this context, we introduce the notion of the trapping redundancy of a code, which quantifies the relationship between the number of redundant rows in any parity-check matrix of a given code and the size of its s

M. Abbrescia, A. Colaleo, R. Guida, G. Iaselli

The Resistive Plate Chambers (RPC) detector of the CMS experiment at the LHC proton collider (CERN, Switzerland) will employ an online gas analysis and monitoring system of the freon-based gas mixture used. We give an overview of the CMS RPC gas system, describe the project parameters and first results on gas-chromatograph analysis. Finally, we report on pre

Y. S. Gui, N. Mecking, X. Zhou, G. Williams

We demonstrate a room temperature spin dynamo where the precession of electron spins in ferromagnets driven by microwaves manifests itself in a collective way by generating d.c. currents. The current/power ratio is at least three orders of magnitude larger than that found previously for spin-driven currents in semiconductors. The observed bipolar nature and

Zlatko Vasilkoski

Contrary to existing theoretical models, experimental evidence points out that electroporation (membrane defect formation under external electric fields) starts to occur within the range of transmembrane voltages that cells may routinely experience, curiously, just above the range of transmembrane voltages involved in neural signal transmission. Understandin

Filipe Moura

We consider a d-dimensional spherically symmetric dilatonic R^2 string corrected black hole solution. We study its stability under tensor type gravitational perturbations and compute the absorption cross section for low frequency gravitational waves.

Young-Rae Kim, Rupert Croft

Using cosmological hydrodynamic simulations we measure the mean transmitted flux in the Lyman alpha forest for quasar sightlines that pass near a foreground quasar. We find that the trend of absorption with pixel-quasar separation distance can be fitted using a simple power law form including the usual correlation function parameters r_{0} and \gamma so that

J. A. Minahan

We explicitly construct the eight fermion zero mode solutions for the Hofman-Maldacena giant magnon. The solutions are naturally gauge fixed under the \kappa-symmetry. Substituting the solutions back into the Lagrangian leads to a simple expression that can be quantized directly. We also show how to construct the SU(2|2)\times SU(2|2) superalgebra from these

Ralf Lehnert

Small violations of spacetime symmetries have recently been identified as promising Planck-scale signals. This talk reviews how such violations can arise in various approaches to quantum gravity, how the emergent low-energy effects can be described within the framework of relativistic effective field theories, how suitable tests can be identified, and what s

J. F. Carinena, K. Ebrahimi-Fard, H. Figueroa, J. M. Gracia-Bondia

The theory of exact and of approximate solutions for non-autonomous linear differential equations forms a wide field with strong ties to physics and applied problems. This paper is meant as a stepping stone for an exploration of this long-established theme, through the tinted glasses of a (Hopf and Rota-Baxter) algebraic point of view. By reviewing, reformul

L. I. Meho

With the vast majority of scientific papers now available online, this paper describes how the Web is allowing physicists and information providers to measure more accurately the impact of these papers and their authors. Provides a historical background of citation analysis, impact factor, new citation data sources (e.g., Google Scholar, Scopus, NASA's Astro

Chiang-Mei Chen, Dmitri V. Gal'tsov, Dmitry G. Orlov

We show that four-dimensional Einstein-Maxwell-Dilaton-Gauss-Bonnet gravity admits asymptotically flat black hole solutions with a degenerate event horizon of the Reissner-Nordstr\"om type $AdS_2\times S^2$. Such black holes exist for the dilaton coupling constant within the interval $0\leq a^2<a^2_{\rm cr}$. Black holes must be endowed with an electric char

Shaul Mukamel

The distribution of work done on a quantum system by instantaneously changing the Hamiltonian is shown to satisfy the Jarzynski identity.

A. S. Belyaev, I. L. Shapiro, M. A. B. do Vale

We explore the potential of the CERN Large Hadron Collider (LHC) to test the dynamical torsion parameters. The form of the torsion action can be established from the requirements of consistency of effective quantum field theory. The most phenomenologically relevant part of the torsion tensor is dual to a massive axial vector field. This axial vector has geom

Gasper Tkacik, Thomas Gregor, William Bialek

Even under constant external conditions, the expression levels of genes fluctuate. Much emphasis has been placed on the components of this noise that are due to randomness in transcription and translation; here we analyze the role of noise associated with the inputs to transcriptional regulation, the random arrival and binding of transcription factors to the

Christian Tanguy

The two- and all-terminal reliabilities of the Brecht-Colbourn ladder and the generalized fan have been calculated exactly for arbitrary size as well as arbitrary individual edge and node reliabilities, using transfer matrices of dimension four at most. While the all-terminal reliabilities of these graphs are identical, the special case of identical edge ($p

F. Haas

We construct an infinite family of one-dimensional equilibrium solutions for purely magnetized quantum plasmas described by the quantum hydrodynamic model. The equilibria depends on the solution of a third-order ordinary differential equation, which is written in terms of two free functions. One of these free functions is associated to the magnetic field con

Nathalie Picqué, Guy Guelachvili, Alexander A. Kachanov

Spectra comprised of hundreds of time-components for absorption path lengths up to 130 km have been recorded around 1050 nm by combining two recent techniques, intracavity laser spectroscopy with vertical external cavity surface emitting multiple-quantum-well lasers and time-resolved Fourier transform spectroscopy. A sensitivity of 1 10^{-10} cm^{-1}.Hz^{-1/

R. B. Govindan

In a recent work Manimaran et al. [Manimaran et al., Phys. Rev. E 72, 046120 (2005)] propose to use multiresolution Daubechies (DB) wavelets to (detrend) remove the low frequency trends and subsequently to quantify the multifractal structure in a given time series. In this comment, by applying DB wavelets to the long range correlated data we show that in the

I. V. Barashenkov, S. R. Woodford

The interaction between a Bloch and a N\'eel wall in the parametrically driven nonlinear Schr\"odinger equation is studied by following the dissociation of their unstable bound state. Mathematically, the analysis focusses on the splitting of a four-fold zero eigenvalue associated with a pair of infinitely separated Bloch and N\'eel walls. It is shown that a

A. Kreyssig, S. Chang, Y. Janssen, J. -W. Kim

X-ray diffraction experiments were performed on polycrystalline and single-crystal specimens of Ce$_{2}$Fe$_{17}$ at temperatures between 10 K and 300 K. Below $T_{\mathrm{t}}$ = 118$\pm$2 K, additional weak superstructure reflections were observed in the antiferromagnetically ordered state. The superstructure can be described by a doubling of the chemical u

Florian Catalin Popa, Ovidiu Tintareanu-Mircea

We investigate higher rank Killing-Yano tensors showing that third rank Killing-Yano tensors are not always trivial objects being possible to construct irreducible Killing tensors from them. We give as an example the Kimura IIC metric were from two rank Killing-Yano tensors we obtain a reducible Killing tensor and from third rank Killing-Yano tensors we obta

E. Sergio Santini

We consider the two-particle wave function of an EPR system given by a two dimensional relativistic scalar field model. The Bohm-de Broglie interpretation is applied and the quantum potential is viewed as modifying the Minkowski geometry. In such a way singularities appear in the metric, opening the possibility, following Holland, of interpreting the EPR cor

Yuriy A. Grigoryev, Andrey V. Tsiganov

We discuss two known constructions proposed by Moser and by Sklyanin of the Darboux-Nijenhuis coordinates for the open Toda lattice.

E. J. Beggs, S. Majid

We introduce the notion of `bar category' by which we mean a monoidal category equipped with additional structure formalising the notion of complex conjugation. Examples of our theory include bimodules over a $*$-algebra, modules over a conventional $*$-Hopf algebra and modules over a more general object which call a `quasi-$*$-Hopf algebra' and for which ex

Runliang Lin, Haishen Yao, Yunbo Zeng

The KdV equation is used as an example to illustrate the relation between the restricted flows and the soliton equation with self-consistent sources. Inspired by the results on the Backlund transformation for the restricted flows (by V.B. Kuznetsov et al.), we constructed two types of Darboux transformations for the KdV equation with self-consistent sources

Dmitri Gal'tsov, Pavel Spirin, Simona Staub

Although consensus seems to exist about the validity of equations accounting for radiation reaction in curved space-time, their previous derivations were criticized recently as not fully satisfactory: some ambiguities were noticed in the procedure of integration of the field momentum over the tube surrounding the world-line. To avoid these problems we sugges

P. D. Grigoriev, A. M. Dyugaev, E. V. Lebedeva

We calculate the contribution to the electron scattering rate from the surface level atoms (SLA), proposed in [A.M. Dyugaev, P.D. Grigoriev, JETP Lett. 78, 466 (2003)]. The inclusion of these states into account was sufficient to explain the long-standing puzzles in the temperature dependence of the surface tension of both He isotopes and to reach a very goo

Jens Christian Claussen

Self-Organizing Maps are models for unsupervised representation formation of cortical receptor fields by stimuli-driven self-organization in laterally coupled winner-take-all feedforward structures. This paper discusses modifications of the original Kohonen model that were motivated by a potential function, in their ability to set up a neural mapping of maxi

Jens Christian Claussen, Jürgen Carstensen, Marc Christophersen, Sergiu Langa

Electrochemical etching of semiconductors, beside technical applications, provides an interesting experimental setup for self-organized structure formation capable of regular, diameter-modulated, and branching pores. The underlying dynamical processes governing current transfer and structure formation are described by the Current-Burst-Model: all dissolution

D. V. Gal'tsov, E. Yu. Melkumova, K. Salehi

We study Cerenkov radiation from moving straight strings which glisse with respect to each other in such a way that the projected intersection point moves faster than light. To calculate this effect we develop classical perturbation theory for the system of Nambu-Goto strings interacting with dilaton, two-form and gravity. In the first order one encounters d

Tania Regimbau

We review the contribution of extra galactic inspiralling double neutron stars, to the LISA astrophysical gravitational wave foreground. Using recent fits of the star formation rate, we show that sources beyond $z_*=0.005$ contribute to a truly continuous background, which may dominate the LISA instrumental noise in the range $3 \simeq 10^{-4}$ - $1 \times 1

Huai-Xiang Huang, You-Quan Li, Jing-Yu Gan, Yan Chen

We use a renormalized mean field theory to study the Gutzwiller projected BCS states of the extended Hubbard model in the large $U$ limit, or the $t$-$t'$-$J$-$J'$ model on a two-dimensional checkerboard lattice. At small $t'/t$, the frustration due to the diagonal terms of $t'$ and $J'$ does not alter the $d_{x^2-y^2}$-wave pairing symmetry, and the negativ

T. Padmanabhan, Aseem Paranjape

The null surfaces of a spacetime act as one-way membranes and can block information for a corresponding family of observers (time-like curves). Since lack of information can be related to entropy, this suggests the possibility of assigning an entropy to the null surfaces of a spacetime. We motivate and introduce such an entropy functional for any vector fiel

Dawood Kothawala, Sudipta Sarkar, T. Padmanabhan

There is an intriguing analogy between the gravitational dynamics of the horizons and thermodynamics. In case of general relativity, as well as for a wider class of Lanczos-Lovelock theories of gravity, it is possible to interpret the field equations near any spherically symmetric horizon as a thermodynamic identity TdS = dE + PdV. We study this approach fur